This core will be responsible for preparing, sectioning and staining samples for routine histology, immuno- and enzyme histochemistry, and in situ hybridization. The core will also provide training to Center investigators and their associates in the use of microtomes, microscopes and in photomicrography. The core will consist of 60% support for a highly experienced SRA III under the supervision of Dr. Kahn. All projects will utilize this core extensively. It will be particularly essential for Project 5 in which tissue, rather than cell cultures, is used exclusively. This must be embedded and section in order to obtain any morphological information. Since Project 3 and 4 propose extensive use of the model for some of their proposed experiments, and since Projects 1 and 2 utilize tissue as well as cell cultures, this core is essential for all investigators.